The disclosure relates a method for automatically adapting a quantity of a coating substance, including a primer that is applied upon printing to a recording medium in a printing system, and a corresponding printing system.
The present disclosure, as well as the underlying problem, are explained in detail in the following using inkjet printing. However, the disclosure is not limited to inkjet printer and is applicable to various other printing methods and/or printing technologies (e.g. liquid toner).
In inkjet printing, a multicolor, contact-less, direct printing takes place that is based on thermal or electrophysical principles. For example, inkjet printing is explained in the publication DE 102 33 409 A1.
Numerous measures exist for quality improvement in inkjet printing. For example, ink in the print heads may age due to too low a throughput. Therefore, regularly interspersed regeneration print images, what are known as refresh lines, are used—in particular in high-capacity printing systems—to regenerate the nozzles (print nozzles) of the print heads between the printing of print data-based print images. For example, this is described in the publication DE 10 2014 108 342 A1.
An additional problem of what is known as “bleeding” or “color bleeding” may occur if an ink of one color is applied onto or in immediate proximity next to an ink of a different color. This problem is expressed in a mixing or merging of the two inks at their interface, whereby the boundary line between the inks becomes unclear, for example blurs at the outer edges. This phenomenon is caused by capillary forces, whereby the printing inks are drawn into adjacent regions. For example, the adhesion of toner particles on the surface of the recording medium may be increased via pre-treatment with a coating substance, such that the bleeding is avoided. This is described in WO 2014/065793 A1, for example.
In the field of a different printing technology, photoelectric liquid toner printing, there also exist printing systems that adapt a property—in particular the composition—of the coating layer applied for pre-treatment of a recording medium during the printing operation, based on a sensor analysis of the print image. A coating substance is hereby adapted in terms of its composition by means of a mixer and is applied onto a recording medium by means of a roller. Such a system is described in DE 10 2015 103 100 B3.
The exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings.